Belt conveyors are in common use in various industrial, mining and agricultural operations. They generally consist of a belt supported all along its length by a series of conveyor idlers. Each conveyor idler consists of a frame on which is mounted one or more freely rotatable cylindrical rollers on which the belt runs. Generally, two or more stub shafts are fixed to the frame. Each end of each cylindrical roller is supported on a stub shaft by a bearing having rolling bearing elements, generally bearing balls. The bearing balls are in turn held between an outer race fixed to the end of the roller and an inner race connected to the stub shaft. It is necessary that the connection between the inner race and stub shaft be non-rotational. Often, this connection is provided by an inner race having a splined bore and a solid stub shaft with grooves cut into the end thereof. The grooves and splines interfit with a small amount of radial and axial play, and give a non-rotatational connection, but require expensive machining.
The belt may be subjected to heavy, varying loads and varying speeds, as will the bearing elements. It would be desirable, therefore, to provide a preload to the bearing to help assure that the load is shared equally among all the bearing elements. A conveyor disclosed in the U.S. Pat. No. 1,362,910 to Zoeller et al shows a bearing assembly with a compression spring loaded against the outer race of a bearing. However, the spring is primarily designed to compensate for wear on the races and to create a braking effect on the roller when the load is removed. This structure is also somewhat complex, requiring an axially slidable outer race and a retaining ring.